Antihalation layers for photographic plates and films



March 30, 1937. w. SCHNEIDER ANTIHALATION LAYERS FOR PHOTOGRAPHIC PLATESAND FILMS Filed oct. 15. l19:51

Supponi- Patented Mar. 3o, 1931 2,075,144

UNITED STATES PATENTA OFFICE ANTIHALATION LAYERS FOR PHOTO- GRAPHICPLATES AND FILMS Wilhelm Schneider, Dessau, Germany, assigner 'to AgfaAnsco Corporation, Binghamton, N. Y., a corporation of New YorkApplication October 15, 1931, Serial No. 569,067 In Germany October 31,1930 My present invention relates to anti-halation Suitable compoundsfor the aforesaid purpose layers for photographic plates and lms, and'are likewise diarylmethanes of the kind described more particularly toa protective layer for an Which bear besides'a carboxyl group orhydroxyl anti-halation layer applied on the back lof such group ahydroxy alkyl group. Furthermore it is 5 plates and films. not necessarythat the diarylmethyl compounds One of its objects is to provide aprocess of prein question are built up symmetrically; one of the ventingparticles to lsplit from the color layer by nuclei may be substituted ifat all by substituents Coating the said layer With a protective layer.otherthan those attached to the other nucleus. Another object are thenew plates or lms being The coating material is usually applied in aprovided with such an improvedv anti-halaton thickness of 0.5-2 which iscompletely sumcient 1o` layer. Further objects will be seen from thedefor protecting the dye-containing anti-halation tailed specificationfollowing hereafter. layer from being mechanically damaged.

The known anti-halation layers applied on the In order to apply thecoating material it is back of photographic plates and films frequentlydissolved in a non-aqueous solvent. Aliphatic deliver colored particleswhen mechanically alcohols have proved to be suitable solvents espe- 15stressed, which deposit in the picture taking cially those containing 1to 5 carbon atoms.

apparatus and, when they come on the light- 'Ihe coating layer caneasily be removed, it Sensitive layer, Cause SpOts by masking the lightbeing soluble in the usual photographic developers or by chemicalinfluence. within about 30 to 40 seconds. vIt may be men- Now I havefound that the said drawback can tioned that those derivatives ofdiarylmethane be avoided by providing the anti-halaton layer, whichcontain only hydroxyl groups more easily containing a coloredanti-halation material diss01ve in developers having a, strong alkalinewhich is permanently removable by an alkaline reaction, whilederivatives of diarylmethane condeveloper bath, with a colorless coatingwhich taining carboxyl groups dissolve in both kinds comprises adiarylmethane derivative containing of developers, those having a strongor those at least one hydroxyl group or carboxyl group in having a weakalkaline reaction. a nucleus. The following compounds are, for Thefollowing examples illustrate my inveninstance, suitable: tion:

. CH l l. A solution of 1 gram of the ammonium saltv T of polyglucuronicacid and 1 gram of fuchsine in 30 (l) 100 cc. of Water is applied on anitrocellulose film.

OH/ j \0H After drying, the anti-halation layer thus ob- (IJOOH 00Htained is coated with a 'solution of 4 grams ofdihydroxydiphenylmethanev dicarboxylic acid (see Formula 1) in 100 cc.of ethanol. 35

on 0H 2. A cenmcse acetate mm is provided with an CH anti-halation layerfrom a solution of 2 grams of (2)v i y gum arabic, 1 gram of methylblue, 50 cc. lof

H3 HI on on on ethanol and 50 cc.,of water. After drying, the

grams of dlhydroxydimethyldiphenyl-methane (Formula 2) in 100 cc. ofpropanol. 4 The quantities of coating solution indicated in CH -GH theexamples allow to coat a. surface of about 2 (3) to 3 square meters. 45

It is to be understood that my invention is not limited to the foregoingexamples norto the cn. specic detalls given therein. Other suitablecolorless coating materials of the kind described (13H3 HB The gurerepresents a sectional view of a photo- 55 graphic plate' preparedaccording to my inveni 55 anti-halation layer is coated with a solutionof 5 40 0H on 0H V cooH\ are considered to be equivalents of those men-5o CH- CH COOH t tioned. Other alcohols than ethanl or propanol (4)likewise may be used. The annexed drawing illustrates my invention.

H: Ha I Ha.

tion. In this ligure' I is the glass plate which serves'as support, 2 isthe emulsion layer, 3 is the color layer forming the anti-halation layeron the back of the plate, and l is my new coating layer 5 preventingparticles of being split off from the color layer.

What I claim is: 1. Photographic plates or films provided on their rearside with an anti-halation layer, said 10 anti-halaton layer'beingcoated with a protection layer comprising a derivative of adiarylmethane substituted with at least one radical of the groupconsisting of -OH and --COOHl 2. Photographic plates or lms provided on15 their rear side with an anti-halation layer, said anti-halationlayer'being coated with a protec-l tion layer comprisingdihydroxydiphenylmethl ane-dicarboxylic acid.

3. 'Photographic plates or iilms provided on 20 their rear side with ananti-halation layer, said anti-halation layer being coated with a'protection layer comprising dihydroxydimethyldiphenylmethane.

4; Photographic plates or iilms comprising a support bearing on one sidea light-sensitive emulsion layer and on the rear side a solid anti.-halation layer containing a colored anti-halation material which ispermanently removable `by an alkaline developer bath, said anti-halationlayer being coated with a protective layer which is insoluble in waterbut soluble in an alkaline developer bath.

5. Photographic plates or lms comprising a support bearing on one side alight-sensitive emulsion layer, and on the rear side, a solidantihalation layer containing a colored anti-halation material, which ispermanently removable by an alkaline .developer bath, said anti-halationlayer being coated with a protective layer, which is insoluble in waterbut soluble in an alkaline developer bath within about -30-40 seconds.

WILHELM SCHNEIDER.

